1. Technical Field
This invention relates to the field of telecommunications services and more particularly to service logic execution environments for telecommunications service providers.
2. Description of the Related Art
The development of the open network application programming interface (API) represents an important departure from traditional methods for opening the architecture of the public switched telephone network (PSTN). One such open network API, the Advanced Intelligent Network (AIN) API and architecture, defines a call model which allows the creation of telecommunications service applications outside of the switch environment. Telecommunications service applications are a'la carte telecommunications applications which can perform enhanced services for a telecommunications session established among two or more parties. Exemplary services applications can include Call Waiting, Caller ID, Call Forwarding, Voice Activated Dialing, and Meet-me Conferencing.
When AIN first had been introduced, in terms of the service application creation process, the AIN architecture represented an important advance. AIN separated service development from switching, allowing service logic components to be developed more quickly and placed in specialized network elements attached to databases. Switches, in turn, being free from all service logic, could be optimized for speed and efficiency. Still, typical service applications developed to the AIN specification are written in specialized languages by specially trained programmers using specialized service creation environments.
Importantly, future telecommunications networks will be characterized by new and evolving network architectures where packet-switched, circuit-switched, and wireless networks are integrated to offer subscribers an array of innovative multimedia, multiparty applications. Equally important, it is expected that the process by which telecommunications applications are developed will change, and will no longer solely be the domain of the telecommunications network or service application provider. In fact, in order to provide a broad portfolio of novel, compelling applications rapidly, service application providers will increasingly turn to third-party applications developers and software vendors. Thus, application development in the telecommunications domain will become more similar to that in software and information technology in general, with customers reaping the benefits of increased competition, reduced time to market, and the rapid leveraging of new technology as it is developed.
To make this vision a reality, the principles of AIN have been discarded in favor of a new service application component development paradigm. Specifically, it has been recognized that future integrated networks must offer application developers a set of standard, open APIs so that applications written for compatibility with one vendor's system can execute in the system of another vendor. In consequence, the cost of applications development can be amortized, reducing the final cost to the customer. Java APIs for Integrated Networks (JAIN) fulfills the requirements of the new service application component development paradigm. Presently, JAIN includes standard, open, published Java APIs for next-generation systems consisting of integrated Internet Protocol (IP) or asynchronous transport mode (ATM) networks, PSTN, and wireless networks. The JAIN APIs include interfaces at the protocol level, for different protocols such as Media Gateway Control Protocol (MGCP), Session Initiation Protocol (SIP), and Transactional Capabilities Application Part (TCAP), as well as protocols residing in the higher layers of the telecommunications protocol stack.
JAIN includes a set of integrated network APIs for the Java platform and an environment to build and integrate JAIN components into services or applications that work across PSTN, packet and wireless networks. The JAIN approach integrates wireline, wireless, and packet-based networks by separating service-based logic from network-based logic. FIG. 1 illustrates a conventional JAIN implementation. As shown in FIG. 1, a conventional JAIN implementation can include a protocol layer 102 which can include interfaces to IP, wireline and wireless signaling protocols. These protocols can include TCAP, ISUP, INAP, MAP, SIP, MGCP, and H.323. The JAIN implementation also can include a signaling layer 103 which can include interfaces to provide connectivity management and call control. The conventional JAIN implementation also can include an application layer 104 for handling secure network access and other external services. Finally, the conventional JAIN implementation can include a service layer 106 which can include a service creation and carrier grade service logic execution environment (SLEE) 108.
In JAIN, the protocol layer 102 and the signaling layer 103 are based upon a Java standardization of specific signaling protocols and provide standardized protocol interfaces in an object model. Additionally, applications and protocol stacks can be interchanged, all the while providing a high degree of portability to the applications in the application layer using protocol stacks from different sources. By comparison, the application layer 104 provides a single call model across all supported protocols in the protocol layer 102. Fundamentally, the application layer 104 provides a single state machine for multiparty, multimedia, and multiprotocol sessions for service components in the application layer 104. This state machine is accessible by trusted applications that execute in the application layer 104 through a call control API.
Notably, applications or services executing at the service level 102 can communicate directly with protocol adapters in the SLEE 108. Protocol adapters typically are class methods, callbacks, event or interfaces that encapsulate the underlying resources such as TCAP, MGCP, etc. The underlying resources can be implemented in many programming languages, but a JAIN-conformant protocol product must provide at least the relevant JAIN API. In contrast, an external application or service executing in the application layer 104 does not have to be aware of the underlying resources and can remain oblivious to the fact that some of its session or call legs may be using different protocols.
Service components 112 are the core JAIN components and can execute in the SLEE 108. More particularly, service components 112 are constructed according to a standard component model and, instantiations of component assemblies execute in coordination with the SLEE 108. Using information regarding the protocol layer 102 which can be incorporated into the SLEE 108, service components 112 can interact with the underlying protocol stacks without having specific knowledge of the protocol stack. Thus, service components 112 can use the call model provided by the signaling layer to implement telephony services. More importantly, the SLEE 108 can relieve the service components 112 of conventional lifecycle responsibilities by providing portable support for transactions, persistence, load balancing, security, and object and connection instance pooling. In this way, the service components 112 can focus on providing telephony services.
Despite the apparent advantages of the JAIN specification, however, conventional implementations of the JAIN specification to date are deficient, particularly in their application to real-time telephony. First, the SLEE of conventional JAIN implementations can incorporate an Enterprise Javabean™ (EJB) approach which includes unnecessary system housekeeping chores, for example lifecycle responsibilities. Lifecycle responsibilities, however, are not as critical in the real-time telephony domain as they are in other communications domains. Thus, the use of EJBs can introduce too many latencies to satisfy the demands of real time operations. More importantly, however, in order to relieve service components of the complexities of the protocol stacks, conventional SLEEs require specific knowledge of the underlying protocol layer.
For instance, including protocol stack information in the SLEE itself during development can add unnecessary complexity to the SLEE. From a lifecycle maintenance perspective this can be problematic. Also, including protocol stack information in the SLEE unnecessarily binds the SLEE to particular underlying protocols. Should it become important to incorporate a new protocol stack in the system, new code must be added to the SLEE. Finally, conventional implementations of the SLEE according to the JAIN specification only permit service components executing therein to receive and respond to events from the protocol layer. More importantly, in a conventional implementation of the SLEE, service components executing in the SLEE cannot communicate with one another.